fix: handle base64 uploads correctly (#64)

### Explanation

_No response_

### Issue

_No response_

### Attestations

- [ ] I have read and agree to the [Code of Conduct](https://docs.nhcarrigan.com/community/coc/)
- [ ] I have read and agree to the [Community Guidelines](https://docs.nhcarrigan.com/community/guide/).
- [ ] My contribution complies with the [Contributor Covenant](https://docs.nhcarrigan.com/dev/covenant/).

### Dependencies

- [ ] I have pinned the dependencies to a specific patch version.

### Style

- [ ] I have run the linter and resolved any errors.
- [ ] My pull request uses an appropriate title, matching the conventional commit standards.
- [ ] My scope of feat/fix/chore/etc. correctly matches the nature of changes in my pull request.

### Tests

- [ ] My contribution adds new code, and I have added tests to cover it.
- [ ] My contribution modifies existing code, and I have updated the tests to reflect these changes.
- [ ] All new and existing tests pass locally with my changes.
- [ ] Code coverage remains at or above the configured threshold.

### Documentation

_No response_

### Versioning

_No response_

Reviewed-on: #64

api/src/app/services/game.service.ts

@@ -10,6 +10,7 @@ import {
   validateUrl,
   validateRating,
   validateStringLength,
+  validateDataUrl,
   MAX_LENGTHS,
 } from "../utils/validation";
 
@@ -42,8 +43,23 @@ export class GameService {
     }
 
     // Validate cover image URL
-    if (data.coverImage && !validateUrl(data.coverImage)) {
-      throw new Error("Invalid cover image URL. Only http and https URLs are allowed.");
+    if (data.coverImage) {
+      if (data.coverImage.startsWith("data:")) {
+        const sizeInBytes = data.coverImage.length * 0.75;
+        if (sizeInBytes > MAX_LENGTHS.DATA_URL) {
+          throw new Error("Cover image must be under 5MB.");
+        }
+        if (!validateDataUrl(data.coverImage)) {
+          throw new Error("Invalid image data URL.");
+        }
+      } else {
+        if (!validateStringLength(data.coverImage, MAX_LENGTHS.URL)) {
+          throw new Error(`Cover image URL must be ${MAX_LENGTHS.URL} characters or less.`);
+        }
+        if (!validateUrl(data.coverImage)) {
+          throw new Error("Invalid cover image URL. Only http and https URLs are allowed.");
+        }
+      }
     }
 
     // Validate tags